For purposes of illustration only, the invention will be described with respect its function in the maintenance of aircraft engines identified as TPE 331-5/-6. Such engines have interstage turbine temperature (ITT) sensor probes which together comprise a built-in thermocouple harness assembly, the assembly being adapted to establish readings of the raw interstage turbine temperature. In one key Maintenance Manual this installed harness assembly is identified as thermocouple assembly. The mode of utility and maintenance of currently existing interstage turbine temperature systems is set forth in Garrett: Maintenance Manual for the TPE 331-5/-6, dated Nov. 29, 1982, and such other procedures as recompensating are set forth at updated pages 588-598.10 inclusive.
In addition to the aforesaid, earlier development in this field has comprised the following U.S. Patent:
(A) F. W. WATERS et al., U.S. Pat. No. 3,348,414, dated Oct. 24, 1967; PA0 (B) W. JURISCH et al., U.S. Pat. No. 3,368,348, dated Feb. 24, 1966; PA0 (C) I. E. MARVIN, U.S. Pat. No. 3,377,848, dated Aug. 22, 1966; PA0 (D) W. R. REYNOLDS et al., U.S. Pat. No. 3,509,768, dated Oct. 12, 1967; PA0 (E) J. I. BLACK, U.S. Pat. No. 3,618,386, dated June 10, 1970; and PA0 (F) R. BOURIGAULT, U.S. Pat. No. 4,186,605, dated Feb. 5, 1980.
Characteristic of the most advanced mode of determining interstage turbine temperature on turboprop engines is U.S. Pat. No. 4,186,605, dated Feb. 5, 1980, entitled Set of Thermocouples for Measuring the Average of Several Temperatures in a Given Space. Such devices are generally disposed adjacent turbine plenum assembly, between first and second stage rotors. The problem with associating such thermocouple probes in the vicinity defined in the engine by the three stators and associated turbines is that upon suspected operational damage to one or more sensors comprising such a probe, it is necessary to break down the entire engine for probe replacement or for examination prior thereto.
Since worn probes have a tendency during operation to short out from center wire to ground, yielding an erroneous average reading of ITT; there is no known means, at present, of determining this operational deterioration or the accuracy of interstage turbine temperature (ITT) by comparison of the raw ITT to the exhaust gas temperature (EGT). Therefore the function of this invention is to graphically establish such a verifying relationship during normal maintenance, without pulling the engine. The second useful function of the present invention, not hitherto conceived, is to enhance recompensation of interstage turbine temperature such as is established in the TPE 331 Maintenance Manual Adjustment and Text section of the aforesaid Garrett publication.